What is the difference between TIA and hemiplegic migraines both come back with neg mri?

Great question. Tia / stroke both characterized by sudden onset of neural deficit, generally as bad as it is going to be at outset. Hm typically have evolving pattern of aura which may progress through stages and involve complicated patterns of neural involvement. Tia less likely to give "positive" symptoms such as paresthesia and visual effects, and less likely to be associated with nausea and headache.